Jan Egeland, the head of the UN humanitarian task force on Syria, said on April 28 that there had been a “catastrophic deterioration” of the situation in Aleppo and parts of Homs during the previous 48 hours.

Speaking after air strikes on rebel-held parts of Aleppo hit a hospital and other buildings, killing more than 60 civilians, Egeland said nobody doubts the severity of the situation.

Egeland said he “cannot express how high the stakes are for the next hours and days” as diplomats try to restore a fragile cease-fire deal that is in tatters.

The French aid group Doctors Without Borders (MSF) said at least 14 patients and six medical workers were among at least 30 people killed by an air strike that destroyed Aleppo’s Al-Qudos hospital late on April 27.

Syria's Army on April 28 denied that it intentionally targeted the hospital.

The Britain-based Syrian Observatory for Human Rights said another air strike on April 28 killed 20 more people in the rebel-held neighborhood.

The latest deaths have raised to more than 150 the number of civilians killed in Aleppo since April 22 by fighting between rebels and the Russian-backed forces of Syrian President Bashar al-Assad and rebels.